The purpose of the research is to document the emergence of the infant's ability to comprehend and complex event relationships that inhere in early language. The investigation focuses specifically on the child's understanding of object functions and of the distinctions between agent and recipient, animate and inanimate, and social and physical causality. To this end, groups of 7, 10, 14, and 20-month-old infants will be tested on six tasks that probe various aspects of these concepts. To assess comprehension, a variant of the familiarization-novelty paradigm will be used in which infants are first exposed to brief videotaped events that are either generalized exemplars or violations of the familiarized concept. The research is expected to contribute to our understanding of the course of cognitive and linguistic development in infancy, and also has potential diagnostic and remedial benefits for the pre-linguistic period.